All the class definitions now go to an area called "Metaspace". GC based on references is faster than it was in PermGen.
Metaspace is in native-memory zone. Its size is unlimited by default. So as long as your machine has enough memory, OOM will not happen.
You can still set a limit to it with parameter "MaxMetaspaceSize". On reaching this size, a GC will be done by the JVM.